The present invention relates to a new and improved construction of apparatus for destacking or unstacking a substantially spiral-shaped formed stack of printed products wherein the printed products bear or contact one another in a partially overlapping arrangement.
Such a "spiral" or "spiral-shaped" stack is illustrated by way of example in FIG. 1 of this disclosure. Apart from the fact that such spiral-shaped stack, in comparison to a conventional stack, constitutes a completely different structure, owing to the spiral-shaped stack formation there are realized considerable practical advantages. A spiral-shaped stack of articles, typically printed products, in comparison to a conventional stack of printed products with the same number of such printed products and the same height, constitutes a uniform and stable structure, or, stated in another way, a spiral-shaped stack with the same stack height contains a greater multiplicity of printed products than a single, conventional stack.
As a general rule, stacks of printed products are directly formed from a so-called fish scale stream or arrangement of printed products, i.e. from a practically endless sequence of printed products which are conveyed in partially overlapping formation. Such a fish scale or imbricated arrangement of printed products or articles also forms an advantageous formation for the transport and further handling of the printed products, in contrast to stacks of such printed products which constitute the formation or arrangement suitable for the storage of the printed products. In the context of this disclosure it is to be understood that the description "fish scale" arrangement as used in connection with the articles which are conveyed, typically printed products, for instance newspapers, is intended to denote an arrangement of substantially flat structures or articles which are disposed in an overlying spread formation, in other words, in the manner of a fanned deck of cards. There are already known in this particular field of technology apparatuses which serve for transforming a fish scale arrangement of products into a conventional stack and, alternatively, for transforming a conventional stack into a fish scale stream or arrangement of such products. These apparatuses are in no way suitable for use in conjunction with a spiral-shaped stack, since the formation thereof is basically different from conventional stacks.
A method and apparatus for the formation of such spiral-shaped stack constitutes subject matter of the commonly assigned, copending United States application Ser. No. 578,357, filed May 6, 1975, entitled "METHOD AND APPARATUS FOR STACKING PRINTED PRODUCTS CONTINUOUSLY ARRIVING IN A SUBSTANTIALLY FISH SCALE OVERLAPPING ARRANGEMENT", listing as the inventors Walter Reist and Werner Honegger, the last-mentioned inventor being one of the co-inventors of this development, and to which reference may be readily had and the disclosure of which is incorporated herein by reference. In order to understand the underlying principles of the present invention it is not necessary to describe in detail the equipment and technique used for forming a spiral-shaped stack of printed products, particularly since the basic formation for such sprial-shaped stack of products will be readily evident from the showing of FIG. 1. Hence, only enough of the arrangement of the spiral-shaped stack will be discussed herein so that those skilled in the art will readily understand the underlying concepts of this development. With the spiral-shaped stack arrangement of products as shown in the formation of FIG. 1, it will be recognized that the fish scale or fanned arrangement of the printed products in the original fish scale stream of such printed products --in contrast to a conventional stack--has not been completely eliminated.